Serum proteins

Serum proteins

Normal valuesTotal serum protein• Total protein: 5.5–9.0 grams per deciliter(g/dL)• Albumin:3.5–5.5 g/dL• Globulin:2.0–3.5 g/dL• Albumin/globulin ratio:Greater than 1.0

ALBUMIN• Is the most abundant protein produced in the liver• Constitutes about half of the blood serum protein it is soluble andmonomeric• Transports hormone , fatty acid• It has half life of approximately 20 day• The gene for albumin is located on chromosome 4And mutation in this gene result in anomalous protein• A low molecular weight protein (M.Wt= 65,000 Dalton)• It prevent leaking the blood from the capillary

Function• Maintains oncotic pressure• Transports thyroid hormones• Transports other hormones, in particular, that are fatsoluble• Transports fatty acids ("free" fatty acids) to the liver andto myocytes for utilization of energy• Transports unconjugated bilirubin• Transports many drugs; serum albumin levels can affectthe half-life of drugs• Competitively binds calcium ions (Ca 2+ )• Buffers pH• Prevents photodegradation of folic acid

PathologyLow blood albumin levels (hypoalbuminemia) canbe caused by:• Liver disease; cirrhosis of the liver is most common• Excess excretion by the kidneys (as in nephrotic syndrome)• Burns (plasma loss in the absence of skin barrier)• Redistribution (hemodilution [as in pregnancy], increasedvascular permeability or decreased lymphatic clearance)• Acute disease states (referred to as a negative acute-phaseprotein)• Mutation causing an albuminemia (very rare)

• Hyperalbuminemia1. this condition is a sign of severe or chronicdehydration.2. It is possible that a retinol (vitamin A) deficiencyalone could cause albumin levels to become raised.Patients recovering from chronic dehydration maydevelop dry eyes as the body uses up its vitamin Astore. It is interesting to note that retinol causescells to swell with water (this is likely one reasonthat too much vitamin A is toxic)3. Hyperalbuminemia is also associated with highprotein diets

How we do albumin analysis?• Add 1 ml of albumin to Bromcresol (green) in the acidicmedium the green color transforms to a greenish to bluecolor and the intensity of the color associated withalbumin concentration and that is measured byspectrophotometricFactors that affect analysis ?• The result is higher if we draw the blood from the patientstanding or after exercise• In case of urinary infections and during the menstrualcycle• After dialysis sessions

Globulin• The globulins are a family of globular proteins that havehigher molecular weights and water solubility thanthe albumins.• Globulin is made up of different proteins called alpha,beta, and gamma types.• Some globulins are made by the liver, while others aremade by the immune system.• Certain globulins bind with hemoglobin and theirglobulins transport metals, such as iron, in the blood andhelp fight infection.• Serum globulin can be separated into several subgroupsby serum protein electrophoresis.

Globulin Can be separated into different fractions on thebasis of their electrophoretic mobility andsedimentation coefficient:• α1-Globulin α1-Fetoproteinα1-Antitrypsin• α2-Globulin α2-FetoproteinHaptoglobin• β-Globulin TransferrinCeruloplasmin• γ-Globulin Antibodies (immunoglobulins)which include (Iga ,Igg ,Igm ,Ige)

• Alpha-1 globulin. The protein portion of high-densitylipoprotein (HDL), the “good” type of cholesterol, isincluded in this fraction.• Alpha-2 globulin. A protein called haptoglobin, that bindswith hemoglobin, is included in the alpha-2 globulinfraction.• Beta globulin. In addition to carrying substances throughthe bloodstream, beta globulin proteins help fightinfection.• Gamma globulin. This proteins is important in preventingand fighting infectionSome gamma globulins bind to foreign substances (suchas virus or bacteria) and destroying them by the immunesystem

High Globulin Levels caused by:1. Chronic inflammatory diseases (ex: TB, Syphilis)2. Bone marrow disorders like multiple myeloma3. Leukemias4. Autoimmunity (Systemic lupus, collagen diseases)5. Rheumatoid arthritis6. Liver disease (biliary cirrhosis, obstructive jaundice)7. Carcinoid syndrome8. Ulcerative colitis9. Kidney disease (Nephrosis)10.Chronic infections (parasites, some cases of viral and bacterialinfection like viral hepatitis or HIV)

Low Globulin Levels caused by:1) Hepatic dysfunction2) Celiac disease3) Proteins are not digested or absorbed properly4) Inflammatory bowel disease (IBD)5) Acute hemolytic anemia6) Hypogammaglobulinemia/Agammaglobulinemia7) Renal disease (A condition in which the kidneys do not filter theprotein from the blood and it leaks into the urine).

MEASUREMENT OF PROTEINFRACTIONS• The protein fraction in plasma can be separated and estimatedusing the following methods:• –Zone electrophoresis• –Immunochemical methods• –Chemical methods• –Ultracentrifugation

UltracentrifugationPhysical Techniques• 1.Ultracentrifugation (analytical or Sedimentationvelocity ultracentrifuge) at 60,000 round per.min.• The boundary between the solvent and the protein isvisualized by an optical system –called (SehlierenSystem).Advantage• Most useful for the determination of the mol. wt ofproteinsDisadvantage• High cost of each analysis and poor resolving capacity(when applied to whole serum or plasma)

Serum protein electrophoresis• This test measures specific proteins in the blood to helpdiagnose some diseases.• Proteins carry a positive or a negative electrical charge,and they move in fluid when placed in an electrical field.• Serum protein electrophoresis uses an electrical field toseparate the proteins in the blood serum into groups ofsimilar size, shape, and charge.

How to Prepare for the Test• The patient may be asked not to eat or drink for 4 hoursbefore a serum protein electrophoresis test.• stop taking drugs that could affect the test. Do not stoptaking any medications without first talking health careprovider.• Drugs that can affect the measurement of total proteinsinclude chlorpromazine, corticosteroids, isoniazid,neomycin, phenacemide, salicylates, sulfonamides, andtolbutamide.

How does it work?• Blood must first be collected, usually into an airtight vialor syringe.• Electrophoresis is a laboratory technique where theblood serum is placed on special paper• The paper is exposed to an electric current to separatethe serum protein components into five classifications bysize and electrical charge, those being serum albumin,alpha-1-globulins, alpha-2-globulins, beta globulins, andgamma globulins.